.\" @(#)des_crypt.3	2.1 88/08/11 4.0 RPCSRC; from 1.16 88/03/02 SMI;
.\"
.Dd October 6, 1987
.Dt DES_CRYPT 3
.Os
.Sh NAME
.Nm des_crypt , ecb_crypt , cbc_crypt , des_setparity
.Nd "fast DES encryption"
.Sh SYNOPSIS
.In rpc/des_crypt.h
.Ft int
.Fn ecb_crypt "char *key" "char *data" "unsigned datalen" "unsigned mode"
.Ft int
.Fn cbc_crypt "char *key" "char *data" "unsigned datalen" "unsigned mode" "char *ivec"
.Ft void
.Fn des_setparity "char *key"
.Sh DESCRIPTION
The
.Fn ecb_crypt
and
.Fn cbc_crypt
functions
implement the
.Tn NBS
.Tn DES
(Data Encryption Standard).
These routines are faster and more general purpose than
.Xr crypt 3 .
They also are able to utilize
.Tn DES
hardware if it is available.
The
.Fn ecb_crypt
function
encrypts in
.Tn ECB
(Electronic Code Book)
mode, which encrypts blocks of data independently.
The
.Fn cbc_crypt
function
encrypts in
.Tn CBC
(Cipher Block Chaining)
mode, which chains together
successive blocks.
.Tn CBC
mode protects against insertions, deletions and
substitutions of blocks.
Also, regularities in the clear text will
not appear in the cipher text.
.Pp
Here is how to use these routines.
The first argument,
.Fa key ,
is the 8-byte encryption key with parity.
To set the key's parity, which for
.Tn DES
is in the low bit of each byte, use
.Fn des_setparity .
The second argument,
.Fa data ,
contains the data to be encrypted or decrypted.
The
third argument,
.Fa datalen ,
is the length in bytes of
.Fa data ,
which must be a multiple of 8.
The fourth argument,
.Fa mode ,
is formed by
.Em OR Ns 'ing
together some things.
For the encryption direction
.Em OR
in either
.Dv DES_ENCRYPT
or
.Dv DES_DECRYPT .
For software versus hardware
encryption,
.Em OR
in either
.Dv DES_HW
or
.Dv DES_SW .
If
.Dv DES_HW
is specified, and there is no hardware, then the encryption is performed
in software and the routine returns
.Er DESERR_NOHWDEVICE .
For
.Fn cbc_crypt ,
the
.Fa ivec
argument
is the 8-byte initialization
vector for the chaining.
It is updated to the next initialization
vector upon return.
.Sh ERRORS
.Bl -tag -width [DESERR_NOHWDEVICE] -compact
.It Bq Er DESERR_NONE
No error.
.It Bq Er DESERR_NOHWDEVICE
Encryption succeeded, but done in software instead of the requested hardware.
.It Bq Er DESERR_HWERR
An error occurred in the hardware or driver.
.It Bq Er DESERR_BADPARAM
Bad argument to routine.
.El
.Pp
Given a result status
.Va stat ,
the macro
.Fn DES_FAILED stat
is false only for the first two statuses.
.Sh AVAILABILITY
The
.Fn ecb_crypt ,
.Fn cbc_crypt ,
and
.Fn des_setparity
functions are part of libtirpc.
.Sh SEE ALSO
.\" .Xr des 1 ,
.Xr crypt 3
.Sh RESTRICTIONS
These routines are not available in RPCSRC 4.0.
This information is provided to describe the
.Tn DES
interface expected by
Secure RPC.
